How to Choose a Laboratory Vacuum Pump

The function of the vacuum pump is to remove gas from the vacuum chamber and reduce the gas pressure in the vacuum chamber to achieve the required vacuum.

Laboratory vacuum pumps are used more and more widely, and most laboratory equipment is equipped with a vacuum pump. Because the vacuum pump is not a single device, it can be used with other instruments. Such as vacuum suction filtration, microbial detection, waste liquid extraction, rotary evaporator, vacuum drying oven, freeze dryer and other equipment. Vacuum pumps are ancillary equipment for each laboratory. Different instruments and equipment have different requirements for vacuum pumps. The following describes the types of vacuum pumps commonly used in the laboratory.

Dry vacuum pumps, also known as oil-free vacuum pumps, are characterized by relying on the machine’s own components to achieve the required vacuum, without contamination and maintenance. The most frequently used vacuum pump in the laboratory is oil-free piston type (used in microbiology laboratories) and corrosion-resistant diaphragm type (used in chemical laboratories).

Non-dry vacuum pumps are generally classified into oil vacuum pumps and water circulation vacuum pumps. The common point of non-dry vacuum pumps is that they need to achieve the desired degree of vacuum by means of other substances (such as water and oil). In the laboratory, the most common pump is an oil-type rotary vane pump, generally work with freeze dryers, vacuum drying ovens, etc.

Laboratory vacuum pump selection

How to choose a vacuum pump for laboratory use? The first thing to understand is the use of the vacuum pump, whether the extracted gas is corrosive. Generally, the sample is filtered, and an oil-free vacuum pump can be selected. For reagent purification, a corrosion-resistant vacuum pump is required. Secondly, the vacuum pump is configured for consideration of other instruments. If it is used to configure the rotary evaporator, it must use a corrosion-resistant vacuum pump. The gas that is volatilized and volatilized is corrosive. If it is used for the drying oven, you can choose a vacuum pump with a higher vacuum, such as the oil pump in a non-dry vacuum pump. .

Vacuum calculation

Most of the vacuum in the laboratory is concentrated above 2 mbar. In the low vacuum field, the pumping time follows the following relationship.

T=V/Se×1.303log10(P1/P2)

formula:

P1 – initial pressure (atmospheric pressure) [Pa]

P2 – achieved pressure [Pa]

T —— pumping time [min]

V——volume [L]

Se – actual pumping speed [L/min]

Considering the pipeline and valve effects, the actual pumping speed is 80% of the theoretical pumping speed.